US20230146009A1 - Molded Parts for Low Temperature Applications, Especially for Liquid Hydrogen - Google Patents

Molded Parts for Low Temperature Applications, Especially for Liquid Hydrogen Download PDF

Info

Publication number
US20230146009A1
US20230146009A1 US17/985,688 US202217985688A US2023146009A1 US 20230146009 A1 US20230146009 A1 US 20230146009A1 US 202217985688 A US202217985688 A US 202217985688A US 2023146009 A1 US2023146009 A1 US 2023146009A1
Authority
US
United States
Prior art keywords
alloy
molded part
parts
impact strength
charpy impact
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US17/985,688
Other languages
English (en)
Inventor
Takayasu Shimizu
Hiroyuki Shimizu
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Japan Silicolloy Industry Co Ltd
Original Assignee
Japan Silicolloy Industry Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Japan Silicolloy Industry Co Ltd filed Critical Japan Silicolloy Industry Co Ltd
Assigned to JAPAN SILICOLLOY INDUSTRY CO., LTD. reassignment JAPAN SILICOLLOY INDUSTRY CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SHIMIZU, HIROYUKI, SHIMIZU, TAKAYASU
Publication of US20230146009A1 publication Critical patent/US20230146009A1/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/007—Heat treatment of ferrous alloys containing Co
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/52—Ferrous alloys, e.g. steel alloys containing chromium with nickel with cobalt
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/001—Austenite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C2202/00—Physical properties
    • C22C2202/02—Magnetic
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/32—Hydrogen storage

Definitions

  • the present invention relates to a method for the production of molded parts, and the molded parts themselves. Furthermore, the use of the molded parts in low-temperature applications is part of the present application.
  • the present invention relates to a molded body made of stainless steel with a high silicon content, which can be produced by casting and used with liquid hydrogen ( ⁇ 253° C.).
  • Hydrogen can be obtained by electrolysis of water or from hydrocarbons. Its energy can be used, for example, by combustion and in fuel cells.
  • the storage of hydrogen is one of the challenges that arise in the further development of hydrogen technology. Because of its low density, hydrogen can only be stored in large quantities under high pressure or as a liquid. Liquid hydrogen is stored at around ⁇ 253° C. Materials that are used in plants for the storage or use of liquid hydrogen must therefore have the necessary mechanical properties at these temperatures. Critical parameters include the yield strength, tensile strength, elongation at break, reduction in area, hardness and toughness and especially the fracture toughness at ⁇ 253° C.
  • JP 2018-104793 A describes austenitic steel with 12.5 to 15.4 percent by weight nickel and less than 1 percent by weight chromium, which is stated to be particularly suitable for tanks for liquid hydrogen.
  • Corresponding steel variants with chromium amounts of 21.5 to 23.5 percent by weight for use in piping for liquid hydrogen are also known under the trade name HRX19.
  • HRX19 Corresponding steel variants with chromium amounts of 21.5 to 23.5 percent by weight for use in piping for liquid hydrogen are also known under the trade name HRX19.
  • a problem with all of these steels, however, is that only forging can provide them with properties that make them suitable for use with liquid hydrogen.
  • As cast steels they have insufficient hardness and/or insufficient fracture toughness. Therefore, molded parts for valves or the like cast therefrom have a short service life.
  • the production of such shaped parts from forged parts by ablative methods is however laborious. Such methods are hardly suitable for mass production. There is therefore a need to further develop hydrogen technology
  • the cast molded parts can be valves or parts thereof.
  • the molded parts should have sufficient hardness and sufficient fracture toughness at ⁇ 253° C.
  • the present invention in one aspect is a method for producing molded parts comprising the following steps:
  • the stainless steel SUS316L is currently used as a standard material for liquid hydrogen.
  • the present invention demonstrates that high silicon stainless steel, which has strength, low temperature toughness, hardness, corrosion resistance, and good abrasion properties, is suitable for use with liquid hydrogen.
  • the present invention makes it possible to use cast steel instead of forged steel.
  • the steel of the present invention contains 2.50 to 4.50% silicon, 10.50 to 19.00% chromium and 13.50 to 20.00% nickel as essential components. It is a stainless steel with high silicon content. Structure and properties are therefore not essentially due to the presence of carbon, as is the case with conventional steel, but to the high proportion of silicon.
  • the steel of the present invention contains a large amount of Si.
  • the Si creates a specific metallographic structure that gives the steel strength. This makes carbon unnecessary.
  • Si also provides the steel with high fracture toughness at ⁇ 253° C., oxidation resistance, corrosion resistance, heat resistance and high-temperatures softening resistance. Si also lowers the melting point of the steel, increases its flowability and thereby improves castability. If its content is below 2.5%, its effect on the above properties is insufficient. A higher content of silicon increases the castability of the melt and leads to more balanced properties of the molded body obtained.
  • the silicon content is therefore preferably at least 3.0%, more preferably at least 3.3% and particularly preferably at least 3.5%. A lower limit of 3.7% is most preferred.
  • the silicon content preferably does not exceed 3.5%, and particularly preferably does not exceed 3.0%. Most preferably, the silicon content ranges from 2.5 to 2.9%.
  • Chromium is a component for ensuring the basic properties, namely corrosion resistance (especially resistance to embrittlement by hydrogen), heat resistance and oxidation resistance, of the stainless steel according to the invention.
  • chromium provides the desired structure of the steel matrix (one-phase structure consisting of austenite or two-phase structure consisting of austenite and ferrite) and thus the desired properties.
  • Chromium also counteracts the embrittlement caused by hydrogen. If the chromium content is less than 10.50%, the effect against embrittlement due to hydrogen is too low. A content of at least 17.00% is preferred in order to obtain a good metallographic structure and to increase the effect against embrittlement by hydrogen.
  • the chromium contents exceed 19.00%, the chromium equivalent defined below becomes large and the austenite content increases. It thus becomes difficult to obtain the desired mechanical properties.
  • Nickel provides the steel with good low-temperature toughness, corrosion resistance, oxidation resistance and heat resistance and is also an element that provides the desired structure of the steel matrix (one-phase structure consisting of austenite or two-phase structure consisting of austenite and ferrite) in combination with Cr.
  • Nickel in particular has a significant influence on the notched impact strength at ultra-low temperatures. In order to achieve a high notched impact strength at around ⁇ 253° C., a content in the range from 13.50% to 20.00% is required. A nickel content in the range from 13.50 to 18.00% is preferred, a content in the range of from 13.50 to 15.00% is especially preferred and a content in the range of from 13.50 to 14.50% is most preferred.
  • nickel also makes the alloy highly resistant to hydrogen embrittlement.
  • nickel is present in large amounts.
  • the nickel content is preferably in the range from 14 to 20%, especially in the range from 15 to 20%.
  • the alloy of the present invention further contains manganese, cobalt and molybdenum in small amounts.
  • Manganese serves as a deoxidizing agent and is at the same time an austenite-forming element and counteracts the embrittlement caused by hydrogen. If the proportions are too high, however, it reduces the corrosion resistance and has a negative influence on the mechanical properties. The proportion of manganese is therefore in the range from 0.50 to 1.50%.
  • Cobalt is also an element that promotes austenite formation. It also increases strength (hardness) and corrosion resistance. These effects become significant at 0.50% and above and increase with increasing content. Cobalt is expensive, however. Therefore, it is present in the range 1.00 to 2.00%. Molybdenum helps improve toughness and wear resistance.
  • Molybdenum is expensive. Therefore, the Molybdenum content should not be more than 1.50%.
  • Carbon, phosphorus, sulfur, and copper have a negative influence on the properties of the alloy of the present invention, and they are preferably not included therein. However, they are often introduced into alloys due to an unavoidable content in commercially available metals. Their amounts must be kept within tight limits.
  • Carbon is an element that increases the strength of steel, and in general, high-strength steels contain a certain amount of carbon as an essential component.
  • the present invention contains a large amount of silicon, which makes the use of carbon unnecessary and undesirable. Carbon lowers the toughness of the steel and adversely affects its machinability, oxidation resistance and corrosion resistance. Therefore, the carbon content should be as low as possible.
  • the amount of carbon in the alloy of the present invention should not exceed 0.050%; preferably it should not exceed 0.030%. Especially preferred is a carbon content of 0.020% and below and most preferred is a carbon content of 0.010% and below.
  • Phosphorous is a typical harmful impurity in stainless steel. It segregates in steel and deteriorates the mechanical properties, the machinability and the corrosion resistance. Therefore, its content should be limited to 0.030% and should be reduced to the lowest possible level. Preferred are 0.015% and most preferred are 0.010%.
  • Sulfur is also a harmful contaminant. It causes the red shortness of steel and thereby reduces the hot machinability of steel. It impairs the cleanliness of the steel due to sulfide inclusions and deteriorates the mechanical properties such as fatigue strength and cursing strength etc. It also reduces corrosion resistance. Therefore, the content of sulfur should be limited to 0.030%, preferably the content should not exceed 0.020%, most preferably and especially in the case of a steel intended for the production of thin wires with a diameter of not larger than 0.1 mm the sulfur content should be limited to 0.005% or less.
  • the present alloy should therefore contain no more than 1.5% copper, preferably no more than 1.0%, particularly preferably no more than 0.70%, very particularly preferably no more than 0.30%.
  • the alloy used in the present process can further contain aluminum, tungsten, nitrogen, oxygen, or hydrogen as unavoidable impurities.
  • the alloy used in the present process comprises preferably not more than 0.01% aluminum, not more than 0.5% of tungsten, not more than 0.03% nitrogen, not more than 0.002% oxygen and not more than 0.0002% hydrogen.
  • the alloy used in the present process is particularly suitable for molded parts that are intended for use with liquid hydrogen. Hydrogen causes hydrogen embrittlement in conventional steels. In the present alloy, however, hydrogen embrittlement is suppressed by a high content of silicon, nickel, chromium and other alloy components. The ability of the elements contained in the alloy to suppress hydrogen embrittlement is expressed by a nickel equivalent yH.
  • the alloy that is used in the process according to the invention preferably has a nickel equivalent yH of at least 24%, where the nickel equivalent yH is calculated according to the formula (1):
  • the alloys according to the invention preferably have a nickel equivalent yH of at least 26.9%. Particularly preferred are those alloys whose nickel equivalent is at least 28.5%. They are practically not affected by hydrogen embrittlement. Most preferably the nickel equivalent is at least 29%.
  • the FIGURE shows the metallographic structure of the steel according to the invention.
  • the alloy has the following composition:
  • Si 3.70 to 4.50%, Cr: 17.00 to 19.00%, Ni: 13.50 to 14.50%, Mn: 0.50 to 1.50%, Co: 1.00 to 2.00%, Mo: 0.50 to 1.50%,
  • the casting is preferably carried out under protective gas and, moreover, preferably according to known procedures with the usual protective devices.
  • the solution heat treatment at a temperature of 1050 to 1150° C. provides the molded parts according to the invention a one-phase structure comprising fine austenite or a two-phase structure comprising fine austenite and ferrite.
  • the molded parts are thus provided with the necessary hardness and overall improved other mechanical properties.
  • This structure provides the molded parts with a high degree of fracture toughness at the lowest temperatures, in particular at ⁇ 253° C. and is particularly resistant to hydrogen embrittlement.
  • temperatures below 950° C. the mixed crystal formation is insufficient and the residual austenite content is too high, which counteracts the increase in strength.
  • the crystal grains become coarse and the toughness decreases.
  • the solution heat treatment usually has the best effects at a temperature in the range from 1050 to 1150° C. It is therefore preferred that the solution treatment is carried out in this temperature range.
  • the temperature ranges for from 950 to 1150° C. and from 1050 to 1150° C. can be applied equally to all processes and all alloys of the present invention.
  • the duration of the solution heat treatment is usually 10 to 60 minutes, preferably 20 to 40 minutes. The best mechanical properties are obtained under these conditions. For larger molded parts, the duration of the heating can be estimated at 1 to 2 hours per inch of thickness of the molded parts.
  • the optimal duration of the solution heat treatment may be determined on the basis of preliminary tests so that the desired properties, in particular the desired hardness and/or fracture toughness of the molded parts, are achieved.
  • the method for cooling after the solution heat treatment is not particularly limited.
  • the cooling can take place, for example, by water cooling, oil cooling or gas cooling.
  • Preferred are water cooling, oil cooling and cooling with liquid nitrogen.
  • Particularly preferred is cooling with water.
  • the molded parts can simply be immersed in water. Cooling to a temperature in the range of 10 to 50° C. is always sufficient. The temperature to which the molded parts must at least be cooled may be determined on the basis of preliminary tests. The temperature at which the properties have reached the necessary values is sufficient. Cooling with water, oil or gas is usually sufficient to achieve the necessary cooling rate. In the case of larger molded parts oil cooling or water cooling may become necessary. Immersion in water or oil with a temperature of 20° C. is usually sufficient to obtain the necessary cooling rate also for large molded parts. The necessary cooling rate can also be determined by preliminary tests.
  • Precipitation hardening is not necessary for the alloys used in the present invention.
  • the FIGURE shows metallographic structures of alloys that are rich in silicon, nickel and chromium and after casting were subjected to a solution heat treatment of 1050° C. for 30 min and then subjected to water cooling.
  • Niobium (Nb) can only be contained in the alloys according to the invention as an unavoidable impurity. As a rule, its content in the alloys according to the invention should be 0% or close to 0%. It has therefore no or almost not influence on the Creq-value.
  • the alloys shown in the diagram contain austenite phases (A) and/or ferrite phases (F).
  • the structure of the alloys used in the present invention is ideal if they are on or above line a and on or above line c in the diagram according to FIG. 1 .
  • a preferred method of the present invention is therefore characterized in that the composition of the alloy obeys the following conditions:
  • a particularly critical property of steels when used at low temperatures is the fracture toughness.
  • Japanese regulations state that steels used for components in liquid hydrogen plants must have a fracture toughness of at least 27 J/cm 2 .
  • the fracture toughness for the purposes of this application is determined in accordance with a notched impact test according to George Charpy (Charpy impact strength).
  • Cast parts made of steels conventionally used for such systems, such as SUS316L cannot meet these requirements or only with a small safety margin. Molded parts that are cast from such steels, for example those that are used in valves, also have only a short service life, which requires frequent and costly maintenance of the systems they are used in. Therefore, complex shaped parts for such systems are often obtained from pieces of forged steel by abrasive methods.
  • a method according to the invention is therefore preferred that is characterized in that the alloy has a fracture toughness of at least 27 J/cm 2 , the fracture toughness being measured in accordance with JIS Z 2242 and at a temperature of ⁇ 253° C., with a cuboid test specimen with a height of and width of 10 mm and a V-shaped notch of 2 mm, with the force acting on the opposite side of the notch.
  • Molded parts of the present invention have particularly preferably a fracture toughness of at least 40 J/cm 2 , very particularly preferably of at least 60 J/cm 2 and most preferably of at least 80 J/cm 2 .
  • the molded parts produced in the process according to the invention can be any desired molded parts.
  • the molded parts are preferably selected from the group consisting of valves, parts of valves, pumps, parts of pumps, turbines, parts of turbines, fittings, parts of fittings, pipes, distributors, connecting pieces, bolts, screws and nuts.
  • valves or parts of valves are also preferably molded parts for use in systems in which liquid hydrogen is stored, transported or processed.
  • the plants in which liquid hydrogen is stored, transported or processed also include, in particular, pipelines, the related plants and other pipeline systems and hydrogen filling stations and the related plants.
  • a method according to the invention is particularly preferred, which is characterized in that the molded parts produced therein are molded parts for use with liquid hydrogen.
  • Another object of the present invention are molded parts produced by the process according to the invention.
  • the manufacturing process according to the invention for molded parts can be used in many ways. It makes all possible shapes accessible through casting, even in mass production. Since the alloy used in the present process contains a large proportion of silicon, the melt of these alloys has a very low viscosity. This makes it possible to cast very thin molded parts down to a thickness of only 1 mm.
  • the molded parts according to the invention can be used in many ways, in particular for apparatuses which are used at low and extremely low temperatures. Since the steels used for the molded parts according to the invention also have high strength, the molded parts can also be used for apparatuses which are under high pressure.
  • the present invention also relates to a valve which comprises or consists of a molded part of the present invention.
  • the present invention also relates to a filling station for supplying vehicles with liquid hydrogen, comprising a molded part according to the invention, in particular comprising a valve which consists of or comprises a molded part according to the invention.
  • Another object of the present invention is the use of molded parts according to the invention, which is characterized in that at least a part of the molded parts has a temperature below ⁇ 200° C.
  • the use of the molded parts and/or valves according to the invention for storing or transporting liquid hydrogen is a preferred embodiment of the present invention.
  • the use of molded parts according to the invention is likewise preferred, which is characterized in that at least a part of the molded parts is in contact with hydrogen.
  • Particularly preferred is the use of molded parts which is characterized in that at least a part of the molded parts are in contact with liquid hydrogen.
  • the use of molded parts which is characterized in that at least a part of the molded parts are in contact with liquid hydrogen, which has a temperature of ⁇ 253° C. or less.
  • the use of the molded parts and/or valves according to the invention for storing or transporting liquid helium is a preferred embodiment of the present invention.
  • Another preferred embodiment of the present invention is the use of molded parts according to the invention, which is characterized in that at least a part of the molded parts are in contact with liquid helium.
  • the helium has a temperature of ⁇ 269° C. or less.
  • Tensile testing A round bar according to JIS No. 14A is subjected to a tensile test at 25° C. on a test machine according to JIS B 7721 according to JIS Z 2241:2011. Yield strength, tensile strength, elongation at break and reduction in area (after fracture) are determined. After measurement, the reduction in area is determined in accordance with JIS G 3199: 2009.
  • Hardness Round bars with a diameter of 20 mm and a thickness of 10 mm were cast and, after mirror polishing, the hardness was determined on a Rockwell hardness tester.
  • Notched impact strength (fracture toughness): V-notched molded parts were produced in accordance with JIS No. 4A, and the Charpy impact strength was determined in accordance with JIS Z 2242 at 20° C., ⁇ 196° C. and ⁇ 253° C. using a testing machine in accordance with JIS B 7722. For measurements at ⁇ 196° C., nitrogen was used for cooling. For measurements at ⁇ 253° C., liquid helium was used for cooling. Block-shaped test specimens with a height and width of 10 mm and a V-shaped notch of 2 mm were used, the force acting on the opposite side of the notch. For the forged steels, forged parts were produced according to the same regulations and the Charpy impact strength was determined at ⁇ 253° C. according to the same regulations with the same device.
  • a number of molded parts were produced from 6 alloys according to the method according to the invention.
  • the alloys were cast into the desired shape and cooled to 25° C.
  • the solution heat treatment was then carried out at 1050° C. for 30 minutes.
  • the molded parts were cooled to 25° C. by immersion in water.
  • Tables 1a and 1b show the composition of the alloys.
  • Table 1a All Elements of Table 1a are required elements for the present invention. All elements of Table 1 b are inevitable impurities, the presence of which is not necessary for the present invention. All values in Tables 1a and 1b are measured values, with the exception of the cobalt content. For Cobalt the weighed-in content is stated. The measurements were carried out with an ARL iSpark 8820 solid-state emission spectroscopy analyzer from ThermoFisher Scientific Inc., Waltham, Ma, USA.
  • Table 2 shows the results of the measurements of the Charpy impact strength in J/cm 2 at 20° C., ⁇ 196° C. and ⁇ 253° C. for the prepared molded parts. For comparison, the Charpy impact strength at ⁇ 253° C. for the corresponding forged molded parts is shown.
  • the Charpy impact strength at ⁇ 253° C. for all alloys is above 27 J/cm 2 . This is unusually high for a cast steel. Alloys 1, 2 and 3 in particular show Charpy impact strength at ⁇ 253° C. of around 100 J/cm 2 or 60 J/cm 2 . These values are well above the required minimum value of 27 J/cm 2 . Molded parts produced from these alloys therefore have a sufficient safety margin with regard to the Charpy impact strength and a long service life.
  • Table 2 also shows that the Charpy impact strength decreases with temperature. Only for Alloy 5, which has a particularly low Charpy impact strength at 20° C., does the Charpy impact strength initially increase at ⁇ 196° C. and then drops sharply to ⁇ 253° C. It can also be seen from Table 2 that the corresponding forged steel from the same alloy has a higher Charpy impact strength at ⁇ 253° C. This corresponds to the behavior of conventional steel.
  • Table 3 shows further mechanical properties of molded parts according to the invention. All values were measured at 20° C.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Heat Treatment Of Articles (AREA)
US17/985,688 2021-11-11 2022-11-11 Molded Parts for Low Temperature Applications, Especially for Liquid Hydrogen Abandoned US20230146009A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102021129414.2 2021-11-11
DE102021129414 2021-11-11

Publications (1)

Publication Number Publication Date
US20230146009A1 true US20230146009A1 (en) 2023-05-11

Family

ID=86053493

Family Applications (1)

Application Number Title Priority Date Filing Date
US17/985,688 Abandoned US20230146009A1 (en) 2021-11-11 2022-11-11 Molded Parts for Low Temperature Applications, Especially for Liquid Hydrogen

Country Status (3)

Country Link
US (1) US20230146009A1 (ja)
JP (1) JP7335017B2 (ja)
DE (1) DE102022129720A1 (ja)

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59104458A (ja) * 1983-11-22 1984-06-16 Shirikoroi Kenkyusho:Kk 高珪素耐熱鋳鋼の改良
JPH11100645A (ja) * 1997-09-26 1999-04-13 Nippon Shirikoroi Kogyo Kk 溶湯の流動性に優れる鋳造用高珪素低炭素ステンレス鋼
JP2954922B1 (ja) * 1998-04-07 1999-09-27 日本シリコロイ工業株式会社 析出硬化型高珪素鋼製品の熱処理方法
WO2002048416A1 (fr) 2000-12-14 2002-06-20 Yoshiyuki Shimizu Acier inoxydable a teneur elevee en silicium
JP2004167595A (ja) 2002-11-22 2004-06-17 Hirotoshi Baba インペラおよびその機械加工方法
JP6760056B2 (ja) 2016-12-28 2020-09-23 日本製鉄株式会社 液体水素用Ｎｉ鋼

Also Published As

Publication number Publication date
JP7335017B2 (ja) 2023-08-29
JP2023071634A (ja) 2023-05-23
DE102022129720A1 (de) 2023-05-11

Similar Documents

Publication Publication Date Title
CA2963770C (en) Austenitic stainless steel and method of manufacturing the same
CN103154291B (zh) 奥氏体系高Mn不锈钢及其制造方法和使用该钢的构件
JP6648646B2 (ja) 低合金鋼材、低合金鋼管および容器、ならびにその容器の製造方法
KR100663720B1 (ko) 오스테나이트계강 용접 조인트
EP3760753B1 (en) Austenitic stainless steel weld joint
CA2509581C (en) High-strength martensitic stainless steel with excellent resistances to carbon dioxide gas corrosion and sulfide stress corrosion cracking
CA2784760C (en) Austenitic stainless steel pipe excellent in steam oxidation resistance and manufacturing method therefor
EP2885440B1 (en) High-chromium heat-resistant steel
CN106893945B (zh) 一种低温用奥氏体不锈钢及其铸件和铸件的制造方法
CN105102653A (zh) 氢用钢结构物、储氢容器及氢用管道的制造方法
JP6648647B2 (ja) 低合金鋼材、低合金鋼管および容器、ならびにその容器の製造方法
EP3677700B1 (en) High-mn steel and production method therefor
EA009108B1 (ru) Двухфазная коррозионно-стойкая легированная сталь для использования в морской воде
JPWO2002048416A1 (ja) 高珪素ステンレス鋼
CN108611561A (zh) 铁素体不锈钢
EP2500444A1 (en) Duplex stainless steel having excellent alkali resistance
JP2016172909A (ja) 高圧水素用容器およびその製造方法
EP3438306B1 (en) Ni-fe-cr alloy
EP2708310A1 (en) Welding material and welded joint
CN108220813B (zh) 一种特超级双相不锈钢及其合金成分优化设计方法
JP5046398B2 (ja) 高窒素マルテンサイト系ステンレス鋼
US20230146009A1 (en) Molded Parts for Low Temperature Applications, Especially for Liquid Hydrogen
KR102463028B1 (ko) 저온충격인성 및 강도가 향상된 고질소 오스테나이트 스테인리스강 및 그 제조방법
Pearce et al. Factors influencing the microstructure and corrosion resistance of austenitic and duplex stainless steel castings
CA3066336C (en) Ni-based alloy pipe for nuclear power

Legal Events

Date Code Title Description
AS Assignment

Owner name: JAPAN SILICOLLOY INDUSTRY CO., LTD., JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SHIMIZU, TAKAYASU;SHIMIZU, HIROYUKI;REEL/FRAME:061744/0829

Effective date: 20221111

STPP Information on status: patent application and granting procedure in general

Free format text: FINAL REJECTION MAILED

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION